The present invention concerns a material structure and absorbent structures or systems which are useful in personal care products such as disposable sanitary napkins, diapers, or incontinence guards. More particularly, the invention relates to absorbent systems that must manage complex viscous body liquids like menses fluid.
Absorbent articles such as feminine pads or sanitary napkins, diapers and incontinent guards are intended to intake and retain body liquids. Current products have deficiencies in these functions that result in higher than desired leakage levels producing stains on clothing. In addition, current products are not perceived to fully deliver on other consumer attributes such as dryness, fit, comfort and confidence. Many of these attributes are effected by the product liquid management performance. Despite continuing improvements in this field, for example, the introduction of xe2x80x9cwingsxe2x80x9d whereby part of a feminine pad wraps around the wearer""s underwear to protect it from leakage, there remains a need for feminine hygiene products with reduced leakage and improved comfort.
Most commercially available pads have relatively high leakage rates. These pads may fail as much as 30 percent of the time, and failure rates of about 20 percent are quite common. Such failures are believed to be due to the highly viscous nature of menses and the great variability in delivery volume which results in overloading of the pad in the target area and subsequent leaking. Insufficient lo distribution of menses is believed to be one of the key causes of the target area overloading.
In the field of urine management in personal care products like diapers, distribution is often provided by materials that have small pores with a narrow pore size distribution. These materials must move the high volume, low viscosity urine insults out of the target area in a time sufficient for the target area to be able to accept the next insult. The movement of urine may be to relatively remote parts of the diaper overcoming substantial hydrostatic pressure. In contrast, feminine hygiene products experience lower total insult volume but the fluid is of greater viscosity, making it more difficult to move the fluid. Distribution materials must be quite different for feminine hygiene products than for products concerned primarily with urine management.
Several examples of improved urine management may be found in U.S. patent application Ser. Nos. 08/754,414 and 08/755,136, commonly assigned, which teach applications of advanced absorbent materials and system designs. While the physics of liquid management is somewhat similar for menses and urine, the complex nature of menses as well as the variability of menses and the product use conditions require significantly different designs for absorbent materials and systems than that required for urine management. Previous attempts to provide lower leakage feminine hygiene products include U.S. Pat. Nos. 5,549,589, 5,466,232 and 5,200,248, which discuss distribution structures for menses. None of these references provide the unique combination of attributes of the instant invention.
It is an object of this invention to provide a feminine hygiene products having superior distribution performance to allow movement of menses from the target area and provide comfort, dry feeling, and lower leakage than traditional pads.
It is an objective of this invention to provide an improved feminine hygiene product which reduces leakage and improves comfort through the use of materials which are designed to accommodate the characteristics of menses and then direct the menses liquid into the absorbent system, substantially isolating it in a localized region of the absorbent system. It is a further object of the invention to provide a feminine hygiene product which has pores which are available and capable of holding adequate amounts of liquid without interfering with intake and distribution.
The object of the invention is achieved by a distribution material comprised of stabilized, highly wettable fibers arranged to provide capillary pore sizes and a degree of wettability ideally suited to wick visco-elastic fluids. When exposed to a visco-elastic fluid and simulants, these materials demonstrate improved fluid distribution performance in terms of the distance wicked, the wicking rate, as well as the amount of fluid moved.
The distribution material for personal care products of this invention is a fabric which wicks artificial menses according to a horizontal wicking test a distance of about 1 inch in less than about 1.5 minutes. Materials meeting this performance criteria generally have a pore size distribution with a high percentage (usually more than about 50 percent) of pore diameters between about 80 and 400 microns and a density below about 0.15 g/cc.
There is also provided a personal care product system having a distribution/retention layer and a pad shaping layer wherein each layer has a stain length ratio of 0.5 or less and the distribution/retention layer has a saturation profile of 4 or less.